The present invention relates to an improved blind riveting assembly and its manufacture. The expression "blind-riveting assembly" is used herein to denote an assembly of a type comprising a flanged rivet body and a mandrel, the mandrel having a stem with expansion means (which may be an integral head or may comprise an integral head or swelling with an expansion sleeve on or adjacent to it) at one end, part of the stem lying within a tubular portion of the rivet body and part, remote from the expansion means, projecting from a head flange at one end of the rivet body, the expansion means of the mandrel being too large to pass through the tubular portion of the rivet body without deforming it, and the arrangement being such that said expansion means and the tubular portion of the rivet body may be inserted through a hole in a workpiece from one side in such a manner that the head flange of the rivet body abuts the workpiece at said one side and part of the tubular portion of the rivet body adjacent said expansion means of the mandrel projects from the other side, and the rivet is set by pulling the mandrel stem at said one side of the workpiece while holding the head flange of the rivet body against the workpiece, thereby causing the expansion means of the mandrel to effect radial expansion of the tubular portion of the rivet body at the other side of the workpiece. The mandrel stem is gripped by a setting tool and is detached at a predetermined breaking point after exceeding a certain pulling force.
The most common variety of blind-riveting assembly is one in which the expansion means is a head of the mandrel integral with the stem, the mandrel head being exposed adjacent to the tail end of the rivet body. Such an assembly is usually made by a method comprising the separate manufacture of mandrel and rivet and their subsequent assembly together in an assembly machine.
Mandrels for blind-rivet assemblies are usually formed from wire fed continuously into a mandrel-forming machine and cut into lengths which are fed into assembly machines where they are assembled with the rivet bodies.
In order to ensure an optimum grip of the setting tool on the mandrel stem, the mandrel stem may be given a modified profile, such as the provision of ridges, grooves and the like which reduce any tendency of the setting tool to slide on the mandrel. Such profile modifications of the mandrel stem can be carried out on the blind-rivet assemblies or on the mandrels prior to assembly.
It is an object of the present invention to provide a blind rivet assembly having a profiled mandrel stem which is simpler to produce.